Multiplying Complex Numbers 2

Directions: Using the integers -9 to 9 at most one time each, fill in the boxes to make a real number product with the greatest possible value.


What is the difference between a real and complex number? What causes an i to go away during multiplication? What causes a term to go away during binomial multiplication? How do we choose integers such that the i terms are additive inverses of one another?


There are two possible answers: (-9 + 6i)(-6 + -4i) and (9 + -6i)(6 + 4i)

Source: Robert Kaplinsky in Open Middle Math

Print Friendly, PDF & Email

Check Also

The Modulus Of A Complex Number

Directions: Using the digits 0 to 9 at most one time each, place a digit …

One comment

  1. How can we prove that this is the biggest product possible?

Leave a Reply

Your email address will not be published. Required fields are marked *